The present invention relates to methods, systems and apparatus for use in wireless (mobile) telecommunications systems. In particular, embodiments of the invention relate to communicating uplink allocations of radio resources from a base station to a terminal device in such systems.
Third and fourth generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architectures, are able to support more sophisticated services than simple voice and messaging services offered by previous generations of mobile telecommunication systems.
For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy third and fourth generation networks is therefore strong and the coverage area needed of these networks, i.e. geographic locations where access to the networks is desired, is expected to increase rapidly.
The anticipated widespread deployment of third and fourth generation networks has led to the parallel development of devices and applications which, rather than taking advantage of the high data rates available, instead take advantage of the robust radio interface and increasing ubiquity of the coverage area. Examples include so-called machine type communication (MTC) applications, which are typified by semi-autonomous or autonomous wireless communication devices (i.e. MTC devices) communicating small amounts of data on a relatively infrequent basis. Examples include so-called smart meters which, for example, are located in a customer's house and periodically transmit information back to a central MTC server relating to the customer's consumption of a utility such as gas, water, electricity and so on. Further information on characteristics of MTC-type devices can be found, for example, in the corresponding standards, such as ETSI TS 122 368 V10.530 (2011 July)/3GPP TS 22.368 version 10.5.0 Release 10) [1]. Some typical characteristics of MTC type terminal devices/MTC type data might include, for example, characteristics such as low mobility, high delay tolerance, small data transmissions, a level of predictability for traffic usage and timing (i.e. traffic profile), relatively infrequent transmissions and group-based features, policing and addressing.
As a result of the increasing use of wireless telecommunications networks generally, and also the development of devices such as MTC devices with their potential for introducing large numbers of terminal devices into networks, there is a desire to provide for wireless telecommunications networks that can reliably support access by increasing numbers of devices. This desire to support more devices, however, gives rise to an increased potential for issues with network congestion and interference, particular in respect of the radio access interface. These issues may be particularly relevant in respect of those communications which are not centrally managed by a scheduler in a communication cell of a network, such as random access communications from terminal devices seeking to access the network before having been allocated dedicated radio resources for doing so.
There is therefore a desire to provide for telecommunications apparatus and methods which can help reduce the potential for radio network congestion and interference in circumstances where there might be relatively large numbers of terminal devices seeking access to the network.